On the function of saturated hydrocarbon compounds as indicators in heavy oil reservoir fire flooding laboratory experiments
Realization of high-temperature oxidation during fire flooding has become one of the difficulties to evaluate the effect of fire flooding in heavy oil reservoirs.To clarify the changing rule of the properties of crude oil after fire flooding,the heavy oil fireflooding experiment was carried out using a three-dimensional indoor physical model,and the saturated hydrocarbons of crude oil after high-temperature oxidation in fire flooding were analyzed by gas chromatography-mass spectrometry(GC-MS).The results showed that after fire flooding,the saturated hydrocarbon content in crude oil increased,causing increased light-to-heavy ratio(∑n C21-/∑n C22+),decreased Pr/n C17 and Ph/n C18;the distribution characteristics and content variation of sterane series were good indicators for high-temperature oxidation in fire flooding.The contents of pregnane and honopreg-nane with high thermal stability increased significantly,and the isomerization parameters of steranes C29(ββ)/(αα+ββ)and C29(20S)/(20S+20R)remained unchanged;the tricyclic terpane/hopane ratio of terpane series increased nearly 2 times after fire flooding,and the C31(22S)/(22S+22R)ratio,which reflected the degree of thermal evolution changed little;β-carotane and γ-carotene were good indicators for high-temperature oxida-tion in fire flooding,and carotene contents decreased greatly after fire flooding.Therefore,the change trend,distribution characteristics and content changes of saturated hydrocarbon compounds in crude oil can effective-ly evaluate the high temperature oxidation of fire drive,and provide strong support for the identification of com-bustion state in fire drive development of heavy oil.
heavy oil reservoirfire floodingburning statushigh temperature oxidationsaturated hydro-carbons
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